It is an object of the present invention to provide ionic compounds in which the anionic charge is delocalized, and their uses.
Derivatives of non-nucleophilic or slightly basic anions have an increasing importance in all applications of chemistry to stabilize or activate various cationic charges such as those of colouring materials or intermediate species in polymerizations. They also act as intermediates for various reactions of organic chemistry. In electrochemistry, media other than water are more and more relied upon for applications such as primary or secondary generators, supercapacitances, systems of modulation of light. The introduction of a weak ionic conductivity in the usual materials (polymers, combustible liquids), enables to disperse electrostatic charges.
Derivatives which are derived from coordination anions of the type BF4xe2x88x92, PF6xe2x88x92, AsF6xe2x88x92, are mainly known, however, they have a limited stability due to dissociation equilibrium releasing the fluoride ion and the corresponding Lewis acid, both causing parasite reactions and presenting a toxicity which is not negligible. The perchlorate anion ClO4xe2x88x92is thermally unstable and dangerous. On the other hand, anions derived from bis(perfluoroalkylsulfonyl)imides which present interesting properties are known. However, this type of chemistry is relatively difficult to control, in particular during the preparation of precursors of the type RFSO2xe2x80x94.
On the other hand, pyrimidinetrione (barbituric acid) and its derivatives which are obtained by replacing an atom of oxygen by an atom of sulfur (thiobarbituric acid) are known. Also known is the possibility to produce salts with 2,2-dimethyl-1,3-dioxane-4,6-dione (xe2x80x9cMeldrum acidxe2x80x9d). In both cases, the acids are relatively weak (pKA) of the order of 5 in water, of the order of 10 in dimethylsulfoxide). Their salts are neither easily soluble nor easily dissociable in organic solvents. In the case of pyrimidinetrione, the hydrogen bonds formed by the protons associated with nitrogen reinforce this insolubility. Their substitution with alkyl radicals strongly decreases the strength of the acid.
The inventors have now found that, surprisingly, the solubility and dissociation of the salts obtained from pyridiminandrione derivatives and its homologues by substitution on the carbon atom in position 5, or on the nitrogens in positions 1 and 3 is considerably increased when the substituents have an electronically attracting power. The same is true with respect to compounds derived from 1,3-dioxane-4,6-diones and their homologues which carry a substituent which is an electroattractor on carbon 2 and/or carbon 5. The choice of substituents and the numerous possible combinations in three substitution sites for each family give various materials for which it is possible to modulate the physical or chemical properties to a large extent. These compounds have interesting properties for the above-mentioned applications and their preparation calls for materials which are more readily accessible. For example, it is possible to obtain stable anionic heterocycles incorporating smaller quantities of fluorine, or to use as starting products fluorinated compounds which are easily accessible. Certain compounds may totally prevent having to rely on fluorine atoms.
A compound of the present invention comprises at least one anionic part associated to at least one cationic part M in sufficient number to ensure an electronic neutrality of the assembly. It is characterized in that M is an hydroxonium, a nitrosonium NO+, an ammonium xe2x80x94NH4+, a metallic cation having a valence m, an organic cation having a valence m or an organometallic cation having a valence m, and in that the anionic part is an aromatic heterocycle corresponding to one of the formulae 
in which:
Y1, Y2, Y3, Y4 and Y5 represent independently from one another a carbonyl group, a sulfonyl group, a thiocarbonyl group, a thionyl group, a xe2x80x94C(xe2x95x90NCN)xe2x80x94 group or a xe2x80x94C(xe2x95x90C(CN)2)xe2x80x94 group;
Z represents an electroattractor radical having a Hammett parameter at least equal to that of a fluorine atom;
each of the substituents RA, RB, RC and RD represents independently from one another a monovalent or trivalent organic radical, or is part of a polymer chain, one at least of the substituents RC and RD being a perfluorinated radical. Preferably, the organic radical has 1 to 20 carbon atoms.
In a compound of the present invention, the cation may be a metallic cation selected from alkali metal cations, alkali-earth metal cations, transition metal cations, trivalent metal cations, rare earth cations. By way of example, there may be mentioned Na+, Li+, K+, Sm3+, La3+, Ho3+, Sc3+, Al3+, Yb3+, Lu3+, Eu3+.
The cation may also be an organometallic cation, for example a metallocenium. By way of example, there may be mentioned cations derived from ferrocene, titanocene, zirconocene, an indenocenium or a metallocenium arene, cations of transition metals complexed with ligands of the phosphine type possibly having a chirality, organometallic cations having one or more alkyl or aryl groups covalently fixed to an atom or a group of atoms, such as methylzinc, phenylmercury, trialkyltin or trialkyllead cations. The organometallic cation may be part of a polymer chain.
According to a variant of the invention, the compounds of the invention have an organic cation selected from the group consisting of R3O+(oxonium), NR4+(ammonium), RC(NHR2)2+(amidinium), C(NHR2)3+(guanidinium), C5R6N+(pyridinium), C3R5N2+(imidazolium), C3R7N2+(imidazolinium), C2R4N3+(triazolium), SR3+(sulfonium), PR4+(phosphonium),IR2+(iodonium), (C6R5)3C+(carbonium). In a given cation, the radicals R may all be identical. However, a cation may also include radicals R which are different from one another. A radical R may be an H or it is selected from the following radicals:
alkyl, alkenyl, oxa-alkyl, oxa-alkenyl, aza-alkyl, aza-alkenyl, thia-alkyl, thia-alkenyl, sila-alkyl, sila-alkenyl, aryl, arylalkyl, alkyl-aryl, alkenyl-aryl, dialkylamino and dialkylazo radicals;
cyclic or heterocyclic radicals possibly comprising at least one lateral chain comprising heteroatoms such as nitrogen, oxygen, sulfur;
cyclic or heterocyclic radicals possibly comprising heteroatoms in the aromatic nucleus;
groups comprising a plurality of aromatic or heterocyclic nuclei, condensed or non-condensed, possibly containing at least one hydrogen, oxygen, sulfur or phosphorus atom.
When an onium cation carries at least two radicals R which are different from H, these radicals may together form an aromatic or non-aromatic cycle, possibly enclosing the center carrying the cationic charge.
When the cationic part of a compound of the invention is an onium cation, it may be either in the form of an independent cationic group which is only bound to the anionic part by the ionic bond between the positive charge of the cation and the negative charge of the anionic part. In this case, the cationic part may be part of a recurring unit of a polymer.
An onium cation may also be part of the radical Z carried by the anionic aromatic nucleus. In this case, a compound of the invention constitutes a zwitterion.
When the cation of a compound of the invention is an onium cation, it may be selected so as to introduce in the compound substituents enabling to confer to said compound specific properties. For example, the cation M+ may be a cationic heterocycle with aromatic character, including at least one nitrogen atom which is alkylated in the cycle. By way of example, there may be mentioned an imidazolium, a triazolium, a pyridinium, a 4-dimethylamino-pyridinium, said cations possibly carrying a substituent on the carbon atoms of the cycle. Among these cations, those which give an ionic compound according to the invention in which the melting point is lower than 150xc2x0 C. are particularly preferred. Such a compound having a low melting temperature is particularly useful for preparing materials with protonic conduction. A particularly preferred material with protonic conduction comprises a compound according to the invention in which the cation is formed by the addition of a proton on the nitrogen or an imidazole or a triazole, as well as the corresponding nitrogenated base in a proportion of 0.5 to 10 in molar ratio.
A compound of the invention in which the cation M is a cationic group having a bond xe2x80x94Nxe2x95x90Nxe2x80x94, xe2x80x94Nxe2x95x90N+, a sulfonium group, an iodonium group, or a substituted or non-substituted arene-ferrocenium, possibly incorporated in a polymeric network, is interesting in as much as it is activatable by a source of actinic energy of appropriate wavelength. Specific examples of such compounds include those in which the cation is a diaryliodonium cation, a dialkylaryliodonium cation, a triarylsulfonium cation, a trialkylaryl sulfonium cation, or a substituted or non-substituted phenacyl-dialkyl sulfonium cation. The above-mentioned cations may be part of a polymer chain.
The cation M of a compounds of the invention may include a group 2,2xe2x80x2[azobis(2-2xe2x80x2-imidazolinio-2-yl)propane]2+ or 2,2xe2x80x2-azobis(2-amidiniopropane)2+. The compound of the invention is then capable of releasing, under the action of heat or an ionizing radiation, radicals which enable to initiate reactions of polymerization, of cross-linking or, in a general manner, chemical reactions involving free radicals. Moreover, these compounds are easily soluble in polymeric and monomeric organic solvents of the same polarity, contrary to the derivatives of anions of the type Clxe2x88x92 which are usually associated with these types of compounds. They present, on the other hand, a negligible vapor pressure contrary to the other free radical initiators of the peroxide or azo type, which is a considerable advantage for preparing polymers in thin films, the volatility of the initiator having as a consequence a bad polymerization or cross-linking of the surface of the film.
The choice of substituents enables to adjust the properties of an ionic compound of the invention.
According to an embodiment of the invention, the substituents RA and RB on the one hand, one of the substituents RC and RD on the other hand, may independently from one another be an alkyl, an alkenyl, an oxa-alkyl, an oxa-alkenyl, an aza-alkyl, an aza-alkenyl, a thia-alkyl, a thia-alkenyl radical, said radicals possibly carrying at least one aryl group.
b) an aryl possibly carrying at least one radical as defined in a);
c) an alicyclic radical or an aromatic radical possibly carrying at least one lateral chain comprising a heteroatom or possibly comprising at least one heteroatom in the cycle;
d) a radical as defined above in a), b) and c) and additionally carrying halogen atoms, in halogenated or perhalogenated form.
Among the above radicals, alkyl radicals and alkenyl radicals having 1 to 10 carbon atoms, halogenated or perhalogenated alkyl or alkenyl radicals having 1 to 10 carbon atoms, and oxa-alkyl or oxa-alkenyl radicals having 1 to 10 carbon atoms are particularly preferred.
The substituent Z may be selected from the group consisting of xe2x80x94F, xe2x80x94Cl, xe2x80x94Br, xe2x80x94CN, xe2x80x94NO2, xe2x80x94SCN and xe2x80x94N3. Z may also be a xe2x80x94CnF2n+1, xe2x80x94Oxe2x80x94CnF2n+1, xe2x80x94Sxe2x80x94CnF2n+1, xe2x80x94CH2xe2x80x94CnF2n+1, OCFxe2x95x90CF2 or xe2x80x94SCFxe2x95x90CF2 radical, 1xe2x89xa6nxe2x89xa68. In addition, Z may be a radical which comprises a heterocycle derived from pyridine, pyrazine, pyrimidine, oxadiazole or thiadiazole, which is fluorinated or non-fluorinated.
According to another embodiment, Z is a radical REYExe2x80x94 or a radical RERGPOxe2x80x94 in which YE represents a carbonyl group, a sulfonyl group, or a thionyl group, and RE and RG represent independently from one another a halogen or an organic radical. The substituents comprising a sulfonyl group are particularly preferred. Each of the substituents RE and RG may represent an alkyl, alkenyl, oxa-alkyl, oxa-alkenyl, aza-alkyl, aza-alkenyl, thia-alkyl, thia-alkenyl, aryl, alkylaryl, alkenylaryl, arylalkyl, arylalkenyl radical, an alicyclic radical or an aromatic radical possibly carrying at least one lateral chain comprising a heteroatom or possibly comprising at least one heteroatom in the cycle, said RE and RG may be halogenated or perhalogenated.
According to an embodiment, RE and RG are selected independently from one another from alkyl or alkenyl radicals having 1 to 12 carbon atoms and possibly comprising at least one heteroatom O, N or S in the main chain or in a lateral chain, and carrying a hydroxy group, a carbonyl group, an amine group, a carboxyl group.
RE and RG may also be selected independently from one another from aryl, arylalkyl, alkylaryl or alkenylaryl radicals, in which the aromatic nuclei, possibly condensed, comprise heteroatoms such as nitrogen, oxygen, sulfur.
In a particular embodiment, one of the groups RE or RG may be a radical having an iodonium group, a sulfonium, oxonium, ammonium, amidinium, guanidinium, pyridinium, imidazolium, imidazolinium, traizolium, phosphonium or carbonium group, said ionic group totally or partially acting as cation M. The compound of the invention then constitutes a zwitterion.
When RE or RG includes at least one ethylenic unsaturation and/or a condensable group and/or a group which is thermally, photochemically or ionically dissociable, the compounds of the invention are reactive compounds which may be subject to polymerizations, cross-linkings or condensations, possibly with other monomers. They may also be used to fix ionophorous groups on polymers carrying the reactive function.
A substituent RE or RG may be a mesomorphous group, or a chromophore group or a self-doped electronically conducting polymer or a hydrolyzable alkoxysilane.
A substituent RE or RG may include a group capable of trapping free radicals such as for example a hindered phenol or a quinone.
A substituent RE or RG may also include a dissociating dipole such as, for example, an amide function, a sulfonamide function or a nitrile function.
A substituent RE or RG may also include a redox couple, for example a disulfide group, a thioamide group, a ferrocene group, a phenothiazine group, a bis(dialkylaminoaryl) group, a nitroxide group or an aromatic imide group.
A substituent RE or RG may include either a complexing ligand or an optically active group.
A substituent RExe2x80x94YExe2x80x94 represents an amino acid, or an optically or biologically active polypeptide.
According to another variant, a compound according to the invention comprises a substituent Z which represents a radical having a valency v higher than two, itself including at least one of the anionic aromatic heterocyclic groups 
In this case, the negative charges present on the anionic part of the compound of the invention may be compensated by the appropriate number of cations or cationic ionophorous groups M.
According to a particular embodiment, the multivalent radical Z is a bivalent radical comprising at least one xe2x80x94SO2xe2x80x94, one xe2x80x94COxe2x80x94 group, one perfluoroalkylene group having 2 to 8 carbon atoms, one phenylene group possibly substituted by heteroatoms, a redox group xe2x80x94(Wxe2x95x90W)nxe2x80x94 or a cationic group xe2x80x94(Wxe2x95x90W)nxe2x80x94W+xe2x80x94 in which W represents a nitrogen atom or a group xe2x80x94C(R)xe2x80x94, R representing an hydrogen atom or an organic radical and 0xe2x89xa6nxe2x89xa65. The presence of the cationic group xe2x80x94(Wxe2x95x90W)nxe2x80x94W+xe2x80x94 gives to the compound of the invention colouring properties which are very useful for lasers. R preferably has 1 to 8 carbon atoms, or two radicals R carried by adjacent carbon atoms forming a cycle. According to an embodiment, Z is part of a recurring unit of a polymer chain. The compound of the invention then presents polyelectrolyte properties.
RE or RG may also be part of a poly(oxyalkylene) radical or a polystyrene radical.
A compound of the present invention in which the anion corresponds to the above general formula A may be prepared according to the following reaction schemes: 
A compound of the present invention in which the anion corresponds to the above general formula B may be prepared by the following reaction scheme: 
In all cases:
L represents a starting electronegative groups selected from F, Cl, Br, N-imidazoyl, N-triazoyl, RFxe2x80x94Oxe2x80x94, RFCH2xe2x80x94Oxe2x80x94 and RFSOXxe2x80x94, RF being a perfluoroalkyl radical;
A represents a cation M+, a triallyl-sylyl group, a trialkyl germanyl group, a trialkylstannyl group or a tertioalkyl group, in which the alkyl substituents have 1 to 6 carbon atoms.
It is advantageous in the case where A=G to permit a displacement of the reaction in the direction of the formation of the compound of the invention by addition of a tertiary or hindered base T capable of forming the salt Lxe2x80x94[HT+] by combination with the proton.
The preferred tertiary bases are in particular selected from alkylamines, for example triethylamine, di-isopropylethylamine, quinuclidine; 1,4 diazabicyclo[2,2,2]octane (DABCO); pyridines, for example pyridine, alkylpyridines, dialkylaminopyridines; imidazoles, for example N-alkylimidazoles, imidazo[1,2,-a]pyridine; amidines, for example 1,5 diazabicyclo[4,3,O]non-5-ene (DBN), 1,8 diazabicyclo[5,4,0]undec-7-ene (DBU); guanidines, for example tetramethyl guanidine, 1,3,4,7,8-hexahydro-1 -methyl-2H-pyrimido[1,2-a]-pyrimidine (HPP).
The use of a compound RCxe2x80x94C(Oxe2x80x94A)2xe2x80x94RD in which A is a tertioalkyl group is advantageous, since such a group is a proton precursor by formation of the corresponding alkene according to the reaction (CH3)3Cxe2x80x94xe2x86x92(CH3)2Cxe2x80x94CH2+Hxe2x80x94.
The use of a compound RCxe2x80x94C(Oxe2x80x94A)2xe2x80x94RD in which A is a trialkylsilyl group is especially interesting when the starting group is a fluorine atom, by reason of the very high stability of the bond Fxe2x80x94Si.
In all these compounds, X represents xe2x80x94CHxe2x80x94 or xe2x80x94C(Z)xe2x80x94. The compounds obtained with Xxe2x95x90CH may then be modified by substitution of the residual proton, for example, by action of trifluoromethane sulfonic anhydride.
In the case where at least one of the Y1 is a group xe2x80x94C(xe2x95x90NCN)xe2x80x94 or a group xe2x80x94C(xe2x95x90C(CN)2)xe2x80x94, the processes to obtain these groups are known to one skilled in the art. By way of example, the reaction of a carbonyl group with cyanamide or malononitrile may be mentioned.
The ionic compounds of the present invention comprise at least one ionophorous group on which substituents which may be quite diverse are fixed. Bearing in mind the large possible choice of substituents, the compounds of the invention enable to produce properties of ionic conduction in most liquid or polymer organic media having a polarity, even low. The applications are important in the field of electrochemistry, in particular for storing energy in primary or s secondary generators, in supercapacitances, in combustible batteries and in electroluminescent diodes. The compatibility of the ionic compounds of the invention with polymers or organic liquids enable to produce noted antistatic properties, even when the content of ionic compound is extremely low. The compounds of the invention which are polymers, as well as polymeric compounds obtained from compounds of the invention having the property of self polymerization or copolymerization, have the above-mentioned properties with the advantage of having a fixed anionic charge. This is why another object of the present invention consists in an ionically conductive material consisting of an ionic compound of the present invention in solution in a solvent.
According to an embodiment, the ionic compound used for preparing an ionically conducting material is selected from compounds in which the cation is ammonium, or a cation derived from a metal, in particular, lithium or potassium, zinc, calcium, rare earth metals, or an organic cation, such as a substituted ammonium, an imidazolium, a triazolium, a pyridinnium, a 4-dimethylamino-pyridinium, said cations possibly carrying a substituent on the carbon atoms of the cycle. The ionically conducting material thus obtained has an elevated conductivity and solubility in solvents, due to low interactions between the positive charge and the negative charge. Its range of electrochemical stability is wide, and it is stable in reducing as well as oxidizing media. Moreover, the compounds which have an organic cation and a melting point lower than 150xc2x0 C., in particular compounds of imidazolium, triazolium, pyridinium, 4-dimethyl-amino-pyridinium have an intrinsic elevated conductivity, even in the absence of solvent, when they are in molten phase.
The properties of the ionically conducting material may also be adapted by the choice of substituents RA, RB, RC, RD, RE and RG.
The choice for at least one of the substituents RA, RB, RC, RD, RE or RG of an alkyl group, an aryl group, an alkylaryl group or an arylalkyl group enables to induce in the ionically conductive material properties of the type mesogene, in particular alkyl groups of 6 to 20 carbon atoms, arylalkyl groups, in particular those containing a biphenyl unit which produce phases of the type liquid crystal. Properties of conduction in phases of the type liquid crystal, nematic, cholesteric or discotic, are interesting for applications relative to optical postings or to reduce the mobility of the anions in the electrolyte, in particular in polymer electrolytes, without affecting the mobility of the cations. This particularity is important for applications in electrochemical generators, in particular those involving lithium cations.
When Z is a mesomorphous group or a group comprising at least one ethylenic unsaturation and/or a condensable group and/or a group which is thermally, photochemically or ionically dissociable, the ionically conductive material easily forms polymers or copolymers which are polyelectrolytes, intrinsically when the polymer carries the solvating groups, or by addition or a polar solvent of the liquid or polymer type, or by mixture with such a solvent. These products have a conductivity which is solely due to the cations, which constitutes a very useful property for applications of the electrochemical generator type. When used in low molar fraction in a copolymer, they induce stable antistatic properties which are little dependent on humidity and promote the fixation of cationic colouring materials, this property being useful for textile fibers and lasers with colouring materials.
The presence of a substituent Z which is a self-doped electronically conductive polymer improves the stability of the ionically conductive material with respect to exterior agents. The conductivity is stable in time, even at elevated temperatures. In contact with metal, these materials give interface resistances which are very weak and in particular protect ferrous metals or aluminum against corrosion.
When a Z is a hydrolyzable alkoxysilane, the ionically conductive material may form stable polymers by the simple mechanism of hydrolysis-condensation in the presence of water, thereby enabling to treat surfaces of oxides, silica, silicates, in particular glass, to produce properties of surface conduction, antistatic properties, or to promote the adhesion of polar polymers.
When a substituent Z is a group comprising a free radical trap such as a hindered phenol, or a quinone, the ionically conductive material has the following advantages and properties: it acts as antioxidant with no volatility and is compatible with polar monomers and polymers, to which it additionally gives antistatic properties.
When Z comprises a dissociating dipole such as an amide, a sulfonamide or a nitrile, the ionically conductive material has an improved conductivity in media of low and medium polarity, in particular in solvating polymers which enables to minimize, even to suppress, the addition of solvents or volatile plasticizing agents.
The presence of a substituent Z which contains a redox couple such as a disulfide, a thioamide, a ferrocene, a phenothiazine, a group bis(dialkylaminoaryl), a nitroxide, an aromatic imide, enables to produce in the ionically conductive material, properties of a redox shuttle which are useful as an element of protection and equalization of charge of electrochemical generators, in photoelectrochemical systems, in particular for the conversion of light into electricity in systems of modulation of light of the electrochrome type.
The presence of a substituent Z which is a complexing ligand in an ionically conductive material enables to chelate metallic cations, in particular those which possess an elevated charge (2, 3 and 4), in the form of soluble complex in organic media, including in aprotic media, and enables the transport of these cations in particular in the form of anionic complex, in solvating polymers. The metallic cations of elevated charge are indeed immovable in solvating polymers. This type of complexing gives with certain cations of transition metals (Fe, Co . . . ) or certain rare earths (Ce, Eu . . . ) particularly stable redox couples.
The ionically conductive materials containing a compound of the invention in which at least one of the substituents RA, RB, RC, RD, RE or RG is an alkyl or alkenyl substituent which contains at least one heteroatom selected from O, N or S have a complexing and plasticizing capacity, in particular in polar polymers and especially polyethers. The heteroatoms N and S are selectively complexing for cations of transition metals, Zn and Pb.
When a substituent alkyl or alkenyl RE or RG additionally carries an hydroxy group, a carbonyl group, an amine group, a carboxyl group, an isocyanate group or a thioisocyanate group, the ionic compound of the invention may give by polycondensation a polymer or a copolymer and the ionically conductive material which contains such a polymer or copolymer has the properties of a polyelectrolyte.
The presence, in the ionically conductive material of the invention, of a compound in which a substituent RE or RG is selected from aryl, arylalkyl, alkylaryl, alkylaryl or alkenylaryl radicals, in which the lateral chains and/or the aromatic nuclei comprise heteroatoms such as nitrogen, oxygen, sulfur, improves dissociation and increases the possibility of forming complexes depending on the position of the heteroatom (pyridine) or the possibility to give by duplicative oxidation conjugated polymers or copolymers (pyrrole, thiophene).
When the ionically conductive material contains a compound of the invention in which a substituent Z represents a recurring unit of a polymer chain, the material constitutes a polyelectrolyte.
A compound of the invention in which the substituent Z is selected from the group consisting of xe2x80x94OCnF2n+1, xe2x80x94OC2F4H, xe2x80x94SCnF2n+1 and xe2x80x94SC2F4H, xe2x80x94OCFxe2x95x90CF2, xe2x80x94SCFxe2x95x90CF2, n being a whole number from 1 to 8, is a precursor of stable monomers and polymers, in particular towards oxygen even at temperatures higher than 80xc2x0 C. when dealing with polymers. An ionically conductive material which contains such a compound is therefore particularly suitable as the electrolyte of a combustible battery.
An ionically conductive material of the present invention comprises an ionic compound of the present invention in solution in a solvent.
The solvent may be an aprotic liquid solvent, a polar polymer or a mixture thereof.
The aprotic liquid solvent is selected for example from linear ethers and cyclic ethers, esters, nitrites, nitro derivatives, amides, sulfones, sulfolanes, alkylsulfamides and partially halogenated hydrocarbons. The solvents which are particularly preferred are diethylether, dimethoxyethane, glyme, tetrahydrofurane, dioxane, dimethyltetrahydrofurane, methyl or ethyl formate, propylene or ethylene carbonate, alkyl carbonates (such as dimethyl carbonate, diethyl carbonate and methylpropyl carbonate), butyrolactones, acetonitrile, benzonitrile, nitromethane, nitrobenzene, dimethylformamide, diethylformamide, N-methylpyrrolidone, dimethylsulfone, fetramethylene sulfone and tetraalkylsulfonamides, having 5 to 10 carbon atoms.
The polar polymer may be selected from cross-linked or non-cross-linked solvating polymers, which may carry grafted ionic groups. A solvating polymer is a polymer which includes solvating units containing at least one heteroatom selected from sulfur, oxygen, nitrogen and fluorine. By way of example of solvating polymers, there may be cited polyethers of linear structure, comb or blocks, which may form a network, based on poly(ethylene oxide), or copolymers containing the unit ethylene oxide or propylene oxide or allylglycidylether, polyphosphazenes, cross-linked networks based on polyethylene glycol cross-linked with isocyanates or networks obtained by polycondensation and carrying groups which enable the incorporation of cross-linkable groups. Block copolymers in which certain blocks carry functions which have redox properties may also be cited. Of course, the above list is non-limiting, and all the polymers having solvating properties may be used.
An ionically conductive material of the present invention may simultaneously comprise an aprotic liquid solvent selected from the aprotic liquid solvents mentioned above and a polar polymer solvent comprising units containing at least one heteroatom selected from sulfur, nitrogen, oxygen and fluorine. It may comprise from 2 to 98% liquid solvent. By way of example of such a polar polymer, polymers which mainly contain units derived from acrylonitrile, vinylidene fluoride, N-vinylpyrrolidone or methyl methacrylate may be mentioned. The proportion of aprotic liquid in the solvent may vary from 2% (corresponding to a plasticized solvent) to 98% (corresponding to a gelled solvent).
An ionically conductive material of the invention may additionally contain a salt which is well known to be used in the prior art for preparing ionically conductive material. Among the salts which may be used in admixture with an ionic compound of the invention, a salt selected from perfluoroalcanesulfonates, bis(perfluoroalkylsulfonyl)imides, bis(perfluoroalkylsulfonyl)methanes and tris(perfluoroalkylsulfonyl)methanes are particularly preferred.
Of course, an ionically conductive material of the invention may additionally contain additives known to be used in this type of material and for example mineral or organic charges in the form of powder or fibers.
An ionically conductive material of the invention may be used as electrolyte in an electrochemical generator. Thus, another object of the present invention is an electrochemical generator comprising. a negative electrode and a positive electrode both separated by an electrolyte, characterized in that the electrolyte is an ionically conductive material as defined above. According to a particular embodiment, such a generator comprises a negative electrode consisting of metallic lithium, or an alloy thereof, possibly in the form of nanometric dispersion in lithium oxide, or a double nitride of lithium and a transition metal, or an oxide of low potential having the general formula Li1+y+x/3Ti2xe2x88x92x/3O4(0xe2x89xa6xxe2x89xa61, 0xe2x89xa6yxe2x89xa61), or carbon and carbonated products derived from the pyrolysis of organic materials. According to another embodiment, the generator comprises a positive electrode selected from vanadium oxides VOx(2xe2x89xa6xxe2x89xa62,5), LiV3O8, LiyNi1xe2x88x92xCoxO2, (0xe2x89xa6xxe2x89xa61; 0xe2x89xa6yxe2x89xa61), spinels of manganese LiyMn1xe2x88x92xMxO2(M=Cr, Al, V, Ni, 0xe2x89xa6xxe2x89xa60,5; 0xe2x89xa6yxe2x89xa62), organic polydisulfides FeS, FeS2, iron sulfate Fe2(SO4)3, phosphates and phosphosilicates of iron and lithium of olivine structure, or substituted products wherein iron is replaced by manganese, used alone or in admixtures. The collector of the positive electrode is preferably aluminum.
An ionically conductive material of the present invention may also be used in a supercapacitance. Another object of the present invention is consequently a supercapacitance utilizing at least one carbon electrode of high specific surface, or an electrode containing a redox polymer in which the electrolyte is an ionically conductive material such as defined above.
An ionically conductive material of the present invention may also be used for doping p or n an electronically conductive polymer and this use constitutes another object of the present invention.
In addition, an ionically conductive material of the present invention may be used as an electrolyte is an electrochrome device. An electrochrome device in which the electrolyte is an ionically conductive material according to the invention is another object of the present invention.
It has been observed that the strong dissociation of ionic species of the compounds of the invention results in a stabilization of carbocations, in particular those in which there is a conjugation with oxygen or nitrogen and, surprisingly, by a strong activity of the proton form of the compounds of the invention on certain monomers. The present invention also has as an object the use of ionic compounds as photoinitiators as sources of Bronsted acid which are catalysts for the polymerization or cross-linking of monomers or prepolymers capable of cationic reaction, or as catalysts for the modification of polymers.
The process of polymerization or cross-linking of monomers or prepolymers capable of cationic reaction is characterized in that there is used a compound of the invention as photoinitiator constituting a source of acid catalyzing the polymerization reaction. The compounds according to the invention in which the cation is a group having a bond xe2x80x94Nxe2x95x90N+, xe2x80x94Nxe2x95x90Nxe2x80x94, a sulfonium group, an iodonium group, or an arene-ferrocenium cation which is substituted or non-substituted. possibly incorporated in a polymeric network, are particularly preferred.
The choice of the various substituents is made so as to increase the solubility of said compound in the solvents used for the reaction of monomers or prepolymers, and as a function of the desired properties for the final polymer. For example, the choice of non-substituted alkyl radicals gives a solubility in low polar media. The choice of radicals comprising an oxa group or a sulfone will give a solubility in polar media. The radicals including a sulfoxide group, a sulfone group, a phosphine oxide group, a phosphonate group, respectively obtained by the addition of oxygen on the atoms of sulfur or phosphorus, may give to the polymer obtained improved properties with respect to adhesion, shine, resistance to oxidation or to WV. The monomers and prepolymers which may be polymerized or cross-linked with the photoinitiators of the present invention are those which may undergo a cationic polymerization.
Among the monomers, those which include a cyclic ether function, a cyclic thioether function or cyclic amine function, vinyl compounds (more particularly vinyl ethers), oxazolines, lactones and lactames may be mentioned.
Among the polymers of the ether or cyclic thioether type, ethylene oxide, propylene oxide, oxetane, epichlorhydrin, tetrahydroflrane, styrene oxide, cyclohexene oxide, vinylcyclohexene oxide, glycidol, butylene oxide, octylene oxide, glycidyl ethers and esters (for example glycidyl methacrylate or acrylate, phenyl glycidyl ether, diglycidylether of bisphenol A or its fluorinated derivatives), cyclic acetals having 4 to 15 carbon atoms (for example dioxolane, 1,3-dioxane, 1,3-dioxepane) and spiro-bicyclo dioxolanes may be mentioned.
Among vinyl compounds, vinyl ethers constitute a very important family of monomers which are capable of cationic polymerization. By way of example, there may be mentioned ethyl vinyl ether, propyl vinyl ether, isobutyl vinyl ether, octadecyl vinyl ether, ethyleneglycol monovinyl ether, diethyleneglycol divinyl ether, butanediol monovinyl ether, butanediol divinyl ether, hexanediol divinyl ether, ethyleneglycol butyl vinyl ether, triethyleneglycol methyl vinyl ether, cyclohexanedimethanol monovinyl ether, cyclohexanedimethanol divinyl ether, 2-ethylhexyl vinyl ether, poly-THF-divinyl ether having a molecular weight between 150 and 5,000, diethyleneglycol monovinyl ether, trimethylolpropane trivinyl ether, aminopropyl vinyl ether, 2-diethylaminoethyl vinyl ether.
Other vinyl compounds may include, by way of example, 1,1-dialkylethylenes (for example isobutene), vinyl aromatic monomers (for example styrene, xcex1-alkylstyrenes, such as xcex1-methylstyrene, 4-vinylanisole, acenaphthene) N-vinyl compounds (for examples N-vinylpyrolidone or N-vinyl sulfonamides).
Among prepolymers, there may be mentioned compounds in which epoxy groups are carried by an aliphatic chain, an aromatic chain, or a heterocyclic chain, for example glycidic ethers of bisphenol A which are ethoxylated by 3 to 15 ethylene oxide units, siloxanes having lateral groups of the epoxycyclohexene-ethyl type obtained by hydrosilylation of copolymers of dialkyl, alkylaryl or diaryl siloxane with methyl hydrogenosiloxane in the presence of vinylcyclohexene oxide, condensation products of the sol-gel type obtained from triethoxy or trimethoxy silapropylcyclohexene oxide, urethanes incorporating the reaction products of butanediol monovinylether and an alcohol of a functionality higher than or equal to 2 with an aliphatic or aromatic di- or tri-isocyanate.
The process of polymerization according to the invention consists in mixing at least one monomer or prepolymer capable of cationic polymerization and at least one ionic compound of the invention, and subjecting the mixture obtained to actinic or xcex2 radiation. Preferably, the reaction mixture is subjected to radiation after having been formed into a thin layer having a thickness lower than 5 mm, preferably in the form of a thin layer having a thickness lower than or equal to 500 xcexcm. The duration of the reaction depends on the thickness of the sample and the power of the source at the active xcex wavelength. It is defined by the speed at which it passes in front of the source, which is between 300 m/min and 1 cm/min. Layers of the final material having a thickness higher than 5 mm may be obtained by repeating many times the operation consisting in spreading a layer and treating it with radiation.
Generally, the quantity of photoinitiator used is between 0.01 and 15% by weight with respect to the weight of the monomer or prepolymer, preferably between 0.1 and 5% by weight.
An ionic compound of the present invention may be used as photoinitiator in the absence of solvent, for example when it is intended to polymerize liquid monomers in which the ionic compound used as photoinitiator is soluble or easily dispersible. This type of utilization is particularly interesting, since it enables to overcome the problems associated with solvents (toxicity, flammability).
An ionic compound of the present invention may also be used as photoinitiator in the form of a homogeneous solution in a solvent which is inert towards polymerization, ready to be used and easily dispersible, in particular in the case where the medium to be polymerized or cross-linked has a high viscosity.
As example of an inert solvent, there may be mentioned volatile solvents, such as acetone, methyl-ethyl ketone and acetonitrile. These solvents will be used merely to dilute the products to be polymerized or cross-linked (to make them less viscous, especially when dealing with a prepolymer). They will be removed by drying after polymerization or cross-linking. Non-volatile solvents may also be mentioned. A non-volatile solvent also serves to dilute the products that one wishes to polymerize or cross-link, and to dissolve the ionic compound of the invention used as photoinitiator, however, it will remain in the material formed and will thus act as plasticizing agent. By way of example, propylene carbonate, xcex3-butyrolactone, ether-esters of mono-, di-, tri-ethylene or propylene glycols, ether-alcohols of mono-, di-, tri-ethylene or propylene glycols, plasticizing agents such as esters of phthalic acid or citric acid may be mentioned.
According to another embodiment of the invention, there may be used as solvent or diluent a compound which is reactive towards polymerization, which is a compound of low molecular weight and of low viscosity which will simultaneously act as polymerization monomer and solvent or diluent for more viscous polymers or prepolymers used in combination. After the reaction, these monomers having been used as solvent will be part of the macromolecular network finally obtained, their integration being wider when dealing with bi-functional monomers. The material obtained after irradiation is now free of products having a low molecular weight and a substantial vapour tension, or capable of contaminating objects with which the polymer is in contact. By way of example, a reactive solvent may be selected from mono and divinyl ethers of mono-, di-, tri-, tetra-ethylene and propylene glycols, N-methylpyrolidone, 2-propenylether of propylene carbonate commercially available for example under the commercial designation PEPC from ISP, New Jersey, United States.
To irradiate the reaction mixture, the irradiation may be selected from ultraviolet radiation, visible radiation, X-rays, xcex3 rays and xcex2 radiation. When ultraviolet light is used as actinic radiation, it may be advantageous to add to the photoinitiators of the invention photosensitizers intended to provide an efficient photolysis with wavelengths less energetic than those corresponding to the maximum of absorption of the photoinitiator, such as those produced by industrial devices, (1≈300 nm for mercury vapour lamps in particular). Such additives are known, and by way of non-limiting example, there may be mentioned anthracene, diphenyl-9, 10-anthracene, perylene, phenothiazine, tetracene, xanthone, thioxanthone, acetophenone, benzophenone, 1,3,5-triaryl-2-pyrazolines and derivatives thereof, in particular derivatives which are substituted on the aromatic nuclei by alkyl, oxa- or aza-alkyl radicals, enabling inter alia to change the absorption wavelength. Isopropylthioxantone is an example of preferred photosensitizer when an iodonium salt according to the invention is used as photoinitiator.
Among the different types of radiation mentioned, ultraviolet radiation is particularly preferred. On the one hand, it is more convenient to use than the other radiations mentioned. On the other hand, photoinitiators are in general directly sensitive towards UV rays and photosensitizers are more efficient when the difference of energy (xcex4xcex) is lower.
The ionic compounds of the invention may also be used in association with free radical initiators produced thermally or by action of actinic radiation. It is also possible to polymerize or cross-link mixtures of monomers or polymers containing functions in which the types of polymerization are different. For example, monomers or prepolymers which polymerize by free radical and monomers or prepolymers which polymerize by cationic polymerization. This possibility is particularly advantageous to produce interpenetrated networks having physical properties which are different from those which would be obtained by a simple mixture of polymers originating from corresponding monomers. Vinyl ethers are not or are very little active by free radical initiation. It is therefore possible, in a reaction mixture containing a photoinitiator according to the invention, a free radical initiator, at least one monomer of the vinyl ether type and at least one monomer comprising non-activated double bonds such as those of the allyl groups, to carry out a separate polymerization of each type of monomer. On the other hand, it is known that monomers which are lacking in electrons, such as esters or amides of farmaric acid, maleic acid, acrylic or methacrylic acid, itaconic acid, acrylonitrile, methacrylonitrile, maleimide and derivatives thereof, form in the presence of vinyl ethers which are enriched in electrons, complexes of transfer of charge giving alternated polymers 1:1 by free radical initiation. An initial excess of vinyl monomers with respect to this stoichiometry enables to preserve polymerizable functions by pure cationic initiation. The start of the activity of a mixture of free radical initiator and cationic initiator according to the invention may be carried simultaneously for the two reactants in the case for example of isolation by actinic radiation of a wavelength for which the photoinitiators of the invention and the selected radical initiators are active, for example at 1=250 nm. By way of example, the following commercial products: Irgacure 184(copyright), Irgacure 651(copyright), Irgacure 261(copyright), Quantacure DMB(copyright), Quantacure ITX(copyright) may be mentioned as initiators.
It may also be advantageous to use the two types of polymerization in a sequential manner, to first form prepolymers which are easy to shape and in which hardening, adhesion, solubility as well as degree of cross-linking may be modified by initiating the activity of the cationic initiator. For example, a mixture of a thermo-dissociable radical initiator and a cationic photoinitiator according to the invention enables to provide sequential polymerizations or cross-linking, first under the action of heat, then under the action of actinic radiation. Similarly, if a free radical initiator and a cationic photoinitiator according to the invention are selected, the first being photosensitive at longer wavelengths than the one initiating the photoinitiator according to the invention, there is obtained a cross-linking in two controllable steps. Free radical initiators may for example be Irgacure(copyright) 651 enabling to initiate free radical polymerizations at wavelength of 365 nm.
The invention also has as an object the use of ionic compounds of the invention for chemical amplification reactions of photoresists in the field of microlithography. During such use, a film of a material comprising a polymer and an ionic compound of the invention is subject to irradiation. The irradiation causes the formation of the acid by replacement of the cation M with a proton, which catalyzes the decomposition or transformation of the polymer. After decomposition or transformation of the polymer on the parts of the film which have been irradiated, the monomers formed or the polymer which has been converted are removed and what remains is an image of the unexposed parts. For this particular application, it is advantageous to use a compound of the invention which is in the form of a polymer consisting essentially of styrenyl recurring units carrying as substituent an aromatic anionic heterocycle. These compounds enable to obtain after photolysis products which are not volatile, and therefore not odoriferous when dealing with sulfides. Among the polymers which may thus be modified in the presence of a compound of the invention, there may for example be cited polymers containing ester units or tertiaryalkyl arylether units, for example poly(phthaldehydes), polymers of bisphenol A and a diacide, polytertiobutoxycarbonyl oxystyrene, polytertiobutoxy-a-methyl styrene, polyditertiobutylfimarate-co-allyltrimethyl-silane and polyacrylates of a tertiary alcohol, in particular tertiobutyl polyacrylate. Other polymers are described in J. V. Crivello et al, Chemistry of Materials 8, 376-381, (1996).
The ionic compounds of the present invention, which have an elevated thermal stability, give numerous advantages with respect to the known salts of the prior art. They have speeds of initiation and propagation which are comparable or higher than those obtained with coordination anions of the type PF6xe2x88x92, AsF6xe2x88x92 and especially SbF6xe2x88x92.
In the compounds of the present invention, the pairs of ions have a very high dissociation, which enables the expression of intrinsic catalytic properties of the cation Mm+, in which the active orbits are easily exposed to substrates of the reaction, especially in different media. Most of the important reactions of organic chemistry may thus be carried out under easy conditions, with excellent yields and the possibility of separating the catalyst from the reaction mixture. The demonstration of asymmetric induction by the use of an ionic compound according to the invention which carries a chiral group is particularly important in view of its generality and its ease of operation. The present invention consequently has as another object the use of compounds of the invention as catalysts in Friedel-Crafts reactions, Diels-Alder reactions, aldolization reactions, additions of Michael, reactions of allylation, reactions of pinacolic coupling, reaction of glycosilation, reaction of openings of the cycle of oxetanes, reactions of metathesis of alkenes, polymerizations of the Ziegler-Natta type, polymerizations of the metathesis type by cycle opening and polymerizations of the metathesis type of acyclic dienes. The preferred ionic compounds of the invention for utilization as catalyst for the above reactions are those in which the cation is selected from lithium, magnesium, copper, zinc, tin, trivalent metals, including rare earths, platinoids, and their organometallic couples, in particular metallocenes.
The compounds of the invention may also be used as solvent to carry out chemical, photochemical, electrochemical, photoelectrochemical reactions. For this particular use, the ionic compounds in which the cation is an imidazolium, triazolium, pyridinium or 4-dimethylamino-pyridinium, are preferred, said cation possibly carrying a substituent on the carbon atoms of the cycle. Among the compounds being used in liquid form, those having a melting point lower than 150xc2x0 C., more particularly lower than 100xc2x0 C., are particularly preferred.
The inventors have also found that the anionic charge carried by the pentacyclic group or the group derived from tetrazapentalene exerts a stabilizing effect on electronic conductors of the conjugated polymer type, and that use of a compound in which one of the substituents comprises a long alkyl chain enables to make these polymers soluble in the usual organic solvents even in doped state. Grafting of these charges on the polymer itself gives polymers in which the global charge is cationic, which are soluble in organic solvents and have, in addition to their stability, properties of anticorrosion towards metals, aluminum and ferrous metals. It is also an object of the present invention to provide electronically conductive material comprising an ionic compound of the present invention in which the cationic part is a polycation constituted of a doped xe2x80x9cpxe2x80x9d conjugated polymer. The preferred ionic compounds for this application are those in which one of the substituents RA, RB, RC, RD, or Z contains at least one alkyl chain having 6 to 20 carbon atoms.
The colouring materials of cationic type (cyanines) are used more and more frequently as sensitizers of photographic films, for storing optical information (optical disks accessible in writing), for lasers. The tendency of these conjugated molecules to pile over one another when they are in solid phase limits their utilization, because of the variation of the optical properties with respect to the isolated molecule. The use of ionic compounds of the invention for manufacturing cationic colouring materials in which the counter ions, possibly bound to this same molecule, correspond to functions of the invention enables to reduce phenomenon of aggregation, including in solid polymer matrices and to stabilize these colouring materials. It is another object of the present invention to provide a composition of cationic colouring material, characterized in that it contains an ionic compound according to the invention. Particularly preferred ionic compounds for this application are those in which the negative charge(s) of the ionic group are either fixed to the molecule of the colouring material, or they constitute the counter-ion of s the positive charges of the colouring material. Other preferred compounds for this application are those in which the radical Z is a bivalent radical comprising at least one cationic group xe2x80x94(Wxe2x95x90W)nxe2x80x94W+xe2x80x94, in which W represents a nitrogen atom or a xe2x80x94C(R)xe2x80x94 group (R being an organic radical) and 0xe2x89xa6nxe2x89xa65.